Computer-assisted planning and execution system

ABSTRACT

A method for computer-assisted planning of a transplant surgery is provided. The method includes obtaining a computer-readable representation of a donor and recipient skeletal fragment; determining surgical cutting planes on the computer-readable representation of the donor skeletal fragment from which a portion of the donor skeletal fragment from the computer-readable representation of the donor skeletal fragment will be harvested; determining virtual cutting guides; performing a virtual osteotomy to separate the portion of the donor skeletal fragment from the computer-readable representation of the donor skeletal fragment from a remainder portion of the donor skeletal fragment based on a position of the virtual cutting guides that are attached to the computer-readable representation of the donor skeletal fragment; positioning the donor skeletal fragment within a transplant region of the recipient skeletal fragment; and creating a hybrid computer-readable representation comprising the recipient skeletal fragment and the portion of the donor skeletal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/651,984, filed Sep. 15, 2019, now allowed, which is a continuation ofU.S. application Ser. No. 15/100,215 filed May 27, 2016, now U.S. Pat.No. 10,448,956, which is a U.S. National Stage application ofPCT/US2014/067671 filed Nov. 26, 2014, which claims priority to U.S.Provisional patent application 61/910,204 filed Nov. 29, 2013, U.S.provisional application 61/940,196 filed Feb. 14, 2014, and U.S.provisional application 62/049,866 filed Sep. 12, 2014, the entiredisclosures of which are hereby incorporated by reference in theirentireties.

GOVERNMENT SUPPORT STATEMENT

This invention was made with government support under Grant Nos.TR000424 and TR001079 awarded by the National Institutes of Health(NIH). The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates generally to the field of surgery, particularlycraniomaxillofacial surgery, and specifically to the field ofcomputer-assisted craniomaxillofacial surgery and all relatedorthognathic, neurosurgical and head/face/neck surgical procedures andassociated methods, tools and systems.

BACKGROUND OF THE INVENTION

Face-jaw-teeth transplantation represents one of the most complicatedscenarios in craniomaxillofacial surgery due to the skeletal, aesthetic,and dental discrepancies between donor and recipient. Use of computertechnology to improve accuracy and precision of craniomaxillofacialsurgical procedures has been described for nearly 30 years, since theincreasing availability of computed topography (CT) prompted thedevelopment of a CT-based surgical simulation plan for osteotomies.

Two broad approaches to computer-assisted surgery (CAS), forcraniomaxiofacial procedures alike, have gained popularity: 1)pre-operative computer surgical planning which may or may not includethe use of three-dimensional computer manufactured surgical guides (3DCAD/CAM) to cut and reposition bone and soft tissue, and 2) utilizingintraoperative, image-based feedback relative to preoperative imagingfor the surgeon to provide more objective data on what is happeningbeyond the “eyeball test”. However, none are meant for real-time guideplacement feedback in areas where accurate guide placement may becomechallenging, such as the three-dimensional facial skeleton. Also, thereare no single platforms built to provide BOTH planning ANDnavigation—with seemless integration Additionally, standardoff-the-shelf vendor computer-assisted surgery systems may not providecustom features to mitigate problems associated with the increasedcomplexity of this particular procedure. Furthermore, there arecurrently no validated methods for optimizing outcomes related to facial(soft tissue), skeletal (hard tissue), and occlusal (dental)inconsistencies in the setting of donor-to-recipient anthropometricmismatch in real-time—a major hurdle to achieving this specialty's fullpotential.

One known system includes pre-operative planning and fabrication ofcutting guides by way of computer manufactured stereolithographic modelsfor human facial transplantation. However, such a system uses standardoff-the-shelf vendor systems and does not include necessary features tomitigate the increased complexity of this particular procedure inregards to accurate guide placement and optimizing outcomes.

Additionally, known CAS paradigms for craniomaxillofacial surgeryprovide little capacity for intraoperative plan updates. This featurebecomes especially important since in some circumstances during thetransplantation surgery, it may be necessary to revise and update thepreoperative plans intraoperatively.

What is needed in the art, therefore, is a single, fully-integratedplatform, providing a computer-assisted surgery solution customized forpre-operative planning, intraoperative navigation, and dynamic,instantaneous feedback for—in the form of biomechanical simulation andreal-time cephalometrics—guide placement and outcome optimization offacial transplantation. Such system has the potential to improveoutcomes across both the pediatric and adult-based patient population.

SUMMARY

In an embodiment, there is a method for performing a medical procedure.The method can include creating a first 3D reconstruction of a skeleton,selecting a cut plane to bisect the 3D reconstruction, and forming areference guide. The reference guide can include an attachment surfaceconfigured for attaching to a skeletal feature, and a navigation surfaceconnected to the attachment surface and comprising a trackable referencegeometry. The attachment surface can include a contoured surfacecorresponding to a geometry defined by the interface of the cut-planeand contours of portions of the skeletal feature. The attachment surfacecan be configured for attaching to the skeleton at a locationsubstantially corresponding to a preselected location.

In another embodiment there is a medical procedure, comprising:attaching a first cranial reference unit to a skeleton; attaching afirst fragment reference unit to a skeleton fragment; tracking locationsof the first cranial reference unit and the first fragment referenceunit with a first tracker; creating a first 3D reconstruction of theskeleton with a first virtual cranial reference unit and first virtualfragment reference unit superimposed on the first 3D reconstruction atlocations that corresponds to relative positions of the first cranialreference unit and the first fragment reference unit; superimposing afirst virtual reference guide on the first 3D reconstruction at alocation that corresponds to a proposed placement of an actual referenceguide relative to the location of the first cranial reference unit orthe location of the first fragment reference unit; forming a firstvirtual fragment by segmenting the 3D reconstruction of the skeleton ata location adjacent to the first virtual reference guide; superimposingthe first virtual fragment on the 3D reconstruction of the skeleton toform a hybrid 3D reconstruction, and performing an automatedcephalometric computation for the hybrid reconstruction.

In another embodiment, there is a computing system for managing medicalprocedures. The system can comprise: at least one memory to store dataand instructions; and at least one processor configured to access the atleast one memory and to execute instructions. The instructions cancomprise: track the locations of a first fragment reference unit withrespect to first cranial reference unit; generating a first 3Dreconstruction of the skeleton with a first virtual cranial referenceunit and first virtual fragment reference unit superimposed on the first3D reconstruction at locations that corresponds to relative positions ofthe first cranial reference unit and the first fragment reference unit;superimposing a planned reference plane over portions of the first 3Dreconstruction; generating a first virtual reference guide having ageometry that corresponds to an interface between intersecting portionsof the planned reference plane and the first 3D reconstruction;controlling a device for manufacturing a reference guide according tothe geometry of the first virtual reference guide; forming a firstvirtual fragment by segmenting the 3D reconstruction of the donorskeleton at a location adjacent to the first virtual reference guide;generating a second 3D reconstruction of the skeleton with the virtualreference guide superimposed on the first 3D reconstruction at alocation that corresponds to a relative position of a reference guide;performing a cephalometric analysis of the first 3D reconstruction andthe second 3D reconstruction; and superimposing the first virtualfragment on the second 3D reconstruction of the skeleton.

Advantages of at least one embodiment include 1) intraoperative planupdates based on hard tissue discrepancies between planned and executedprocedure; 2) on-table feedback in the form of dynamic, real-timecephalometrics; and 3) pre-designed fixation plates matching the virtualplan.

Another advantage of at least one embodiment includes increasing therobustness of conventional CAS paradigms by providing a robust surgicalsystem to deal with situations in which tools and templates designed andfabricated preoperatively may not entirely address intraoperativesurgical needs. Robustness of the planning and navigation strategy isespecially important in total face transplantation given the longoperating times.

Another advantage of at least one embodiment includes improved outcomesand decreased accompanying morbidity via shortened operative times, moreprecise surgical maneuvers, and improved margin of safety.

A computer-implemented method for computer-assisted planning of atransplant surgery is disclosed. The method can comprise obtaining acomputer-readable representation of a donor skeletal fragment; obtaininga computer-readable representation of a recipient skeletal fragment;determining one or more surgical cutting planes on the computer-readablerepresentation of the donor skeletal fragment from which a portion ofthe donor skeletal fragment will be harvested from the computer-readablerepresentation of the donor skeletal fragment; determining one or morevirtual cutting guides based on the one or more surgical cutting planesto be attached to the computer-readable representation of the donorskeletal; performing a virtual osteotomy to separate the portion of thedonor skeletal fragment from the computer-readable representation of thedonor skeletal fragment from a remainder portion of the donor skeletalfragment based on a position of the one or more virtual cutting guidesthat are attached to the computer-readable representation of the donorskeletal fragment; positioning the donor skeletal fragment within atransplant region of the recipient skeletal fragment; creating a hybridcomputer-readable representation comprising the recipient skeletalfragment and the portion of the donor skeletal fragment during or afterthe positioning; and providing the hybrid computer-readablerepresentation as an output.

The computer-implemented method can further comprise creating thecomputer-readable representation of a recipient skeletal fragment basedon one or more medical imaging techniques, wherein the computer-readablerepresentation of the recipient skeletal fragment comprises one or moreof: a vascular model or a neural model of the recipient skeletalfragment; and creating the computer-readable representation of a donorskeletal fragment based on one or more medical imaging techniques,wherein the computer-readable representation of the donor skeletalfragment comprises one or more of: a vascular model or a neural model ofthe donor skeletal fragment.

The computer-readable representation of the recipient skeletal fragmentand the donor skeletal fragment can comprise a segmented 3Dreconstruction model that is created using the one or more medicalimaging techniques and a segmentation algorithm, wherein each voxel ofthe segmented 3D reconstruction model of the recipient skeletal fragmentand the donor skeletal fragment comprises an associated anatomicalattribute that classifies an anatomy for which each voxel represents.

The computer-implemented method can further comprise tracking movementof the donor skeletal fragment of the computer-readable representationduring the positioning; updating the hybrid computer-readablerepresentation based on the movement being tracked.

The computer-implemented method can further comprise identifying a setof cephalometric landmarks associated with the hybrid computer-readablerepresentation; calculating a set of cephalometric metrics for the setof cephalometric landmarks that are identified; and determining anacceptable result of the surgery being planned based at least in part onthe set of cephalometric metrics that are calculated.

The set of cephalometric landmarks can comprise one or more of: Gonion(“Go”), Nasion (“N”), A point (“A”), B point (“B”), Sella (“S”), Menton(“M”), left/right Zygoma (“ZY”), Os occipital (“OCC”).

The computer-implemented method can further comprise updating at leastone of the one or more surgical cutting planes or cutting guides basedon the determination of acceptable result.

The computer-implemented method can further comprise comparing the setof cephalometric metrics that were calculated based on a set of baselinecephalometric metrics.

A system for computer-assisted planning of a transplant surgery isdisclosed. The system can comprise at least one memory storinginstructions; and at least one processor coupled to the memory andexecuting the instructions to perform a method of computer-assistedplanning of a transplant surgery. The method can comprise obtaining acomputer-readable representation of a donor skeletal fragment; obtaininga computer-readable representation of a recipient skeletal fragment;determining one or more surgical cutting planes on the computer-readablerepresentation of the donor skeletal fragment from which a portion ofthe donor skeletal fragment from the computer-readable representation ofthe donor skeletal fragment will be harvested; determining one or morevirtual cutting guides based on the one or more surgical cutting planesto be attached to the computer-readable representation of the donorskeletal fragment; performing a virtual osteotomy to separate theportion of the donor skeletal fragment from the computer-readablerepresentation of the donor skeletal fragment from a remainder portionof the donor skeletal fragment based on a position of the one or morevirtual cutting guides that are attached to the computer-readablerepresentation of the donor skeletal fragment; positioning the donorskeletal fragment within a transplant region of the recipient skeletalfragment; creating a hybrid computer-readable representation comprisingthe recipient skeletal fragment and the portion of the donor skeletalfragment during or after the positioning; and providing the hybridcomputer-readable representation as an output.

A non-transitory computer-readable medium including instructions toperform a method for computer-assisted planning of a transplant surgeryis disclosed. The method can comprise obtaining a computer-readablerepresentation of a donor skeletal fragment; obtaining acomputer-readable representation of a recipient skeletal fragment;determining one or more surgical cutting planes on the computer-readablerepresentation of the donor skeletal fragment from which a portion ofthe donor skeletal fragment from the computer-readable representation ofthe donor skeletal fragment will be harvested; determining one or morevirtual cutting guides based on the one or more surgical cutting planesto be attached to the computer-readable representation of the donorskeletal fragment; performing a virtual osteotomy to separate theportion of the donor skeletal fragment from the computer-readablerepresentation of the donor skeletal fragment from a remainder portionof the donor skeletal fragment based on a position of the one or morevirtual cutting guides that are attached to the computer-readablerepresentation of the donor skeletal fragment; positioning the donorskeletal fragment within a transplant region of the recipient skeletalfragment; creating a hybrid computer-readable representation comprisingthe recipient skeletal fragment and the portion of the donor skeletalfragment during or after the positioning; and providing the hybridcomputer-readable representation as an output.

Additional advantages of the embodiments will be set forth in part inthe description which follows, and in part will be understood from thedescription, or may be learned by practice of the invention. Theadvantages will be realized and attained by means of the elements andcombinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description, serve to explain the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of general features of a surgical system of anembodiment closes the loop between surgical planning, navigation andenabling intraoperative updates to the plan.

FIGS. 2A-2C provide a schematic overview of a surgical system of anembodiment.

FIGS. 2D-2G are graphical representations of some components and/orfeatures of the surgical system of FIGS. 2A-2C.

FIG. 3 is a flow chart depicting a procedure associated with use of thesurgical system, for example, the surgical system of FIGS. 2A-2C.

FIG. 4A is a CT-scan of reconstructed images of size-mismatched facialskeleton generated from segmentation software utilized for pre-operativeplanning.

FIG. 4B shows a Segmented arterial system of craniomaxillofacialskeleton generated from CT angiography (CTA) data allowing 3D,intraoperative mapping.

FIGS. 5A-5B shows depictions of on-screen images provided by a surgicalsystem, such as the surgical system of FIG. 2A displaying real-time,dynamic cephalometrics and pertinent measurements applicable to humans.FIG. 5A shows donor's face-jaw-teeth alloflap in suboptimal position ascompared to recipient's cranium FIG. 5B shows appropriate face-jaw-teethpositioning with immediate surgeon feedback and updated cephalometricdata pertinent to a pre-clinical investigation. A surgeon may adjust theposition of face-jaw-teeth segment upwards, downwards, forwards orbackwards based on this real-time cephalometric feedback—since thisinformation helps to predict optimal form and function. For instance,placing the face-jaw-teeth segment forward may improve the patient'sairway, but if moved too far forward, it may cause at the same time thepatient to have a significant overjet (i.e. malocclusion) and abnormalappearance on profile view.

FIG. 6 shows some pre-bent fixation plates with screw holes designedvirtually to accommodate the donor-to-recipient skeletal mismatch areasand matching navigational cutting guides of a surgical system, forexample, the surgical system of FIGS. 2A-2C.

FIG. 7A depicts a kinematic reference mount of an embodiment as it isaffixed onto a donor's cranium with intermaxillary screws. A permanentsuture (not visible) attaches stabilizers, such as springs and/or crossbars, which allow easy removal and replacement during surgery.

FIG. 7B depicts a detachable rigid body with reflective markers attachedto the reference body

FIGS. 8A-8C include illustrations of cutting guides of the embodimentswith navigational capabilities. FIG. 8A illustrates a donorface-jaw-teeth alloflap recovery, FIG. 8C shows recipient preparationprior to transplant, FIG. 8C illustrates custom pre-bent fixation plateand palatal splint designed to achieve face-jaw-teeth alignment andskeletal inset with standard technique.

FIG. 9A-9D include photographs and renderings showing exemplary surgicalresults according to embodiments.

FIGS. 10A-10C are top-view (bird's eye view), left-sided profile view,and frontal view, respectively, of images displayed by an imaging systemof a surgical system of the embodiments. The images depict a recipientskeleton and include real-time assessment of planned versus actualface-jaw-teeth positions.

FIGS. 11A-11B are “on screen” images displayed by an imaging sub-systemof a surgical system of the embodiments. The images depict an ideallocation of a cutting guide versus actual position and an actual insetposition of donor alloflap for aesthetic, dental and skeletal relationin size-mismatched donors due to anterior translation of cutting guide.

FIGS. 12A-H illustrate virtual osteotomy and planned cut plane placementon virtual representations of a skeletal feature.

FIGS. 13A-D show virtual placement of a cutting guide alongsidephotographs of an actual placement.

FIG. 14A illustrates a perspective view of a variation of a cuttingguide, for example, a variation of the cutting guide of FIG. 13.

FIG. 14B illustrates a top view of a variation of a cutting guide, forexample, a variation of the cutting guide of FIG. 13.

FIG. 15 illustrates an example method of a computer-implemented methodfor computer-assisted planning of a transplant surgery, according to thepresent teachings.

FIG. 16 illustrates an example schematic view of such a computing orprocessor system that can perform the methods disclosed herein,according to an embodiment.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all sub-ranges subsumedtherein. For example, a range of “less than 10” can include any and allsub-ranges between (and including) the minimum value of zero and themaximum value of 10, that is, any and all sub-ranges having a minimumvalue of equal to or greater than zero and a maximum value of equal toor less than 10, e.g., 1 to 5. In certain cases, the numerical values asstated for the parameter can take on negative values. In this case, theexample value of range stated as “less that 10” can assume negativevalues, e.g. −1, −2, −3, −10, −20, −30, etc.

The following embodiments are described for illustrative purposes onlywith reference to the Figures. Those of skill in the art will appreciatethat the following description is exemplary in nature, and that variousmodifications to the parameters set forth herein could be made withoutdeparting from the scope of the present invention. It is intended thatthe specification and examples be considered as examples only. Thevarious embodiments are not necessarily mutually exclusive, as someembodiments can be combined with one or more other embodiments to formnew embodiments.

Disclosed are embodiments of a computer-assisted surgery system thatprovides for large animal and human pre-operative planning,intraoperative navigation which includes trackable surgical cuttingguides, and dynamic, real-time instantaneous feedback of cephalometricmeasurements/angles as needed for medical procedures, such as facialtransplantation, and many other instances of craniomaxillofacial andorthognathic surgery. Such a system can be referred to as acomputer-assisted planning and execution (C.A.P.E.) system and can beexploited in complex craniomaxillofacial surgery like Le Fort-based,face-jaw-teeth transplantation, for example, and any type oforthognathic surgical procedure affecting one's dental alignment, andcan include cross-gender facial transplantation.

The fundamental paradigm for CAS involves developing a surgical plan,registering the plan and instruments with respect to the patient, andcarrying out the procedure according to the plan. Embodiments describedherein include features for workstation modules within a CAS paradigm.As shown in FIG. 1, a surgical system of the embodiments can enableintraoperative evaluation of a surgical plan and can provideinstrumentation for intraoperative plan updates/revisions when needed.

Embodiments can include a system with integrated planning and navigationmodules, for example, a system for tracking donor and recipient surgicalprocedures simultaneously. In general, features of such a system caninclude: 1) two networked workstations concurrently used in planning andnavigation of the two simultaneous surgeries for both donor andrecipient irrespective of geographic proximity. 2) two trackers, such aselectromagnetic trackers, optical trackers (e.g., Polaris, NDI Inc.),and the like, for tracking bone fragments, tools, and soft tissues, 3)novel guides, reference kinematic markers, etc. as required fornavigation. These features are described in further detail with respectto FIGS. 2A-2G.

Preoperative planning can include the following tasks: a) segmentationand volumetric reconstruction of the donor and recipient facial anatomy;b) planning for patient-specific cutting guide placement; c)cephalometric analysis and biomechanical simulation of the hybridskeleton's occlusion and masticatory function, respectively; d)Fabrication of the hybrid cutting guides enabling both geometric(“snap-on” fit) and optical navigation; e) 3D mapping the vascularsystem on both recipient and donor facial anatomy; f) plan updates, ifnecessary, based on the feedback from the intraoperative module. As usedherein, “snap-on fit” or “snap-on” or “snap on” is used to describe theway an item, such as a cutting guide, attaches to a pre-determined area.That is, the cutting guide actually “snaps-on” to a certainpre-determined area along the facial skeleton, and in all other areas itdoesn't fit properly since size and width varies throughoutsignificantly with many convexities and concavities.

Intraoperative tasks of embodiments described herein can generallyinclude: 1) registration of the preoperative model reconstructed fromthe CT data to donor and recipient anatomy; 2) visualization (usinginformation from the tracker, such as an electromagnetic tracker,optical tracker, and the like) of the instruments and cutting guides tohelp the surgeon navigate; 3) verify the placement of cutting guides,and performing real-time cephalometric and biomechanical simulation forocclusion analysis, if, for any reason, the osteotomy sites need to berevised; 4) dynamically tracking the attachment of the donor fragment tothe recipient and provide quantitative and qualitative (visual) feedbackto the surgeon for the purpose of improving final outcomes related toform (i.e. overall facial aesthetics) and function (i.e. mastication,occlusion relation, airway patency). Such a procedure is described infurther detail below with respect to FIG. 3.

Preoperative Planning

In general, a method for performing a surgery includes a virtualsurgical planning step that includes performing segmentation and 3Dreconstruction of recipient and donor CT scans (e.g., Mimics 15.01,Materialise, Leuven Belgium). Virtual osteotomies can then be performedwithin the software to optimize the donor/recipient match.Patient-customized cutting guide templates can then be created (3-matic7.01, Materialize, Leuven, Belgium). These templates can then be rapidprototyped via an additive manufacturing modeling process, which caninclude, but is not limited to, stereolithography or 3D printing and thelike. The surgical method and system for performing surgery aredescribed in further detail below.

Referring to FIGS. 4A and 4B, during the initial planning stage,surgeons determine a virtual plan 401 based on the recipient'scraniomaxillofacial deformity irrespective of the donor. From registeredCT data, segmentation software generates volume data for specific keyelements (e.g., the mandible, maxilla, and cranium) used forpreoperative planning and visualization. The planning workstationautomatically generates the expected cut geometry of the donor fragment402 together with the recipient, thereby defining the predicted facialskeleton with accompanying hybrid occlusion. If available, blood vessels404 are segmented from CT angiography scans as shown in FIG. 4B. Thatis, in an embodiment nerves (via known nerve foramens) and vessels (botharteries and veins) can be localized to provide a full anatomical “roadmap” to the surgeons for a more precise, time-saving anatomicaldissection with perhaps decreased blood loss and smaller incisions. Theplanning module can also perform static cephalometric analysis andevaluation of face-jaw-teeth harmony via biomechanical simulation onvarying constructions of the hybrid donor and recipient jaw, such asthat shown in FIGS. 5A-5B. Using this tool, the surgeon can evaluatedifferent placements for the donor's face-jaw-teeth alloflap on therecipient's facial skeleton in relation to orbital volumes, airwaypatency, facial projection, and dental alignment. An automatedcephalometric computation for the hybrid face indicates the validity ofthe planned surgery from both an aesthetic, functional andreconstructive standpoint based on various measurements of pertinentlandmarks as shown, for example, in Tables 1A-B.

TABLE 1A Pertinent landmarks for cephalometric analysis. Note that anyother cephalometric landmark and/or angle can also be used with thisCAPE system. SYMBOL NAME and DEFINITION Go Gonion: a point mid-waybetween points defining angles of the mandible Gn Gnathion: most convexpoint located at the symphysis of the mandible ALV Alveolare: mid-lineof alveolar process of the upper jaw, at incisor - alveolar junction LIBLower Incisor Base: midline of anterior border of alveolar process ofmandible at the incisor- alveolar junction PA Parietale: most superioraspect of skull in the midline, (formed by nuchal crest of occipitalbone and parietal bone) PRN Pronasale: bony landmark representinganterior limit of nasal bone ZY Zygion: most lateral point of malar boneOCC Occipital region: midpoint between the occipital condyles

TABLE 1B Cephalometric measurements and related units. Measure LIB- PA-PA- ALV- ZY- PA- Go- Go- PA- LIB- OCC- PA- PRN- PRN- PRN- ZY PRN Gn LIBALV ALV Overbite Overjet PRN ALV ALV LIB LIB Units mm mm mm Mm mm mm mmmm mm deg deg deg deg

To evaluate and predict cephalometric relationships both during planningand intra-operative environments, the system can use validated,translational landmarks between swine and human to thereby alloweffective pre-clinical investigation. The cephalometric parametersdefined by these landmarks can be automatically recalculated as thesurgeon relocates the bone fragments using a workstation's graphicaluser interface.

Preoperative planning can also involve fabrication of custom guides 207as shown in FIG. 6 and palatal splints 223 as illustrated in FIG. 8C.Planned cut planes 403 (as shown in FIG. 4) can be used for defining thegeometry of the cutting guides to thereby provide patient-specificcutting guides. These cutting guides can be designed according to theskeletal features through which the cutting plane intersects, such as anouter skeletal surface of a cross section defined by the cutting plane,and can be fabricated via stereolithography, or via any additivemanufacture technology. In an embodiment, custom cutting guide templatescan be separately designed and navigational registration elements can beadded (Freeform Plus, 3D Systems, Rock Hill, S.C.). As discussed above,the surgical guides can be manufactured via additive manufacturingtechnology (AMT). The cutting guides can, therefore, be a 3D printingmaterial such as a polymer, and can include an attachment surface 216configured for attaching to a skeletal feature, and can have a “snap-on”fit to both donor and recipient. As described above, the attachmentsurface comprises a contoured surface that corresponds to contours ofthe skeletal feature within the planned cut planes. A navigationsurface, such as a reference geometry 217 connected, built into, orattached to the guide structure directly or via attachment guides (notshown) enables dynamic intraoperative tracking of guides with respect tothe patient's skeleton. Palatal splints ensure planned dento-skeletalalignment fixation following Le Fort-type facial transplants or anysimilar type of surgery. Fixation plates 216 can include a primarysurface 216′ and a plurality of fixation surfaces 221, such as eyelets,for screw placement to provide rigid immobilization at the irregularskeletal contour areas along various donor-to-recipient interfaces.Having pre-bent fixation plates decreases total operative times andhelps to confirm accurate skeletal alignment by overcoming step-offdeformities at bone-to-bone interfaces. Accordingly, at least one of theplurality of fixation surfaces can be located on one side of the primarysurface and configured for attaching the fixation surface to a donorskeleton fragment, and at least one of another of the plurality offixation surfaces is located on another side of the primary surface andconfigured for attaching the fixation surface to a recipient skeleton.The whole fixation plate or just portions of the fixation plate, such asthe primary surface or fixation surfaces can be manufactured viaadditive manufacturing technology.

The cutting guide's navigation surface can include trackable objects,for example, on the reference geometry, such as infrared (IR) reflectivecoatings or IR emitters. For example, the trackable objects can includea plurality of integrated tracking spheres, each of which has an IRreflection surfaces.

Intraoperative Surgical Assistance

Individual navigation for both donor and recipient surgeries tracks thecutting guides with respect to planned positions. Surgeons can attach areference unit, such as a kinematic reference mount to threeintramedullary fixation (IMF) screws arranged in a triangular pattern oneach the donor and recipient craniums as shown in FIG. 7A-7B.Accordingly, in an embodiment, there is a reference unit 205 forproviding real-time surgical navigation assistance. The reference unitfor providing real-time surgical navigation assistance can include akinematic mount 203, at least one fixation rod 202, at least one support204, and reference geometry 201. The kinematic mount 203 can include abase with a plurality of recesses defined by sidewalls 233, at least onepair of slots 235 defined by portions of the sidewalls, with each slotof the pair formed across the recess from the other slot, and at leastone guide hole 237 extending through a length of the fixation plate. Theat least one fixation rod 202 can extend through the at least one guidehole 237. An end of the at least one support rod can be configured forattaching to a skeleton of a being 209. The at least one support can bedisposed in the pair of slots and can be configured to attach to thebeing. The reference geometry 201 can be attached to the at least onefixation rod.

The at least one support 204 can include at least one cross-bar 204′with ends that are configured for placement in the slots 235, and aspring 204″ attached at one end to the at least one cross-bar 204′ andattached at another end to the patient (e.g., a human-being). The springattached at another end to the being can be attached via a suture(further described below). The 205 can further include a trackableobject disposed on the reference geometry. The trackable object disposedon the reference geometry can include an IR reflective surface. Themount 203 can be made via additive manufacturing techniques and cantherefore comprise a polymer. The at least one fixation rod can includea plurality of intramedullary fixation screws. The base can beconfigured for being detachably mounted on the skeleton of the being.The intramedullary fixation screws can be arranged in a triangularpattern. Accordingly the guide-holes can be configured in a triangularpattern on the base.

Accordingly, the mount design permits flexibility in the placement ofthe IMF screws so that no template is necessary. A spring 204″ canattach to each IMF screw via suture threaded through, for example, theeyelets. These springs hold the cranial mount 203 in place and alloweasy removal and replacement of the cranial mount (e.g. duringpositional changes required for bone cuts and soft tissue dissections).The key design advantages of the reference are detachability and use ofIntramaxillary fixation (IMF) screws for stable attachment.

The reference geometry 201 (e.g., which can be purchased from Brainlab,Westchester, Ill., USA) attached to the kinematic mount 203 provides astatic coordinate frame attached to the patient. The surgeon candigitize three bony landmarks (e.g. the inferior aspect of the orbitsand antero-superior maxilla) to define a rough registration between theenvironment and virtual models. For example, three, consistent pointscan be selected which can be quick to find, easy to reproduce onnumerous occasions, and would remain constant irrespective of the userand his/her experience with the systems of the embodiments. The surgeoncan thereby collect several point sets from exposed bone using adigitization tool and uses an iterative closest point registrationtechnique to refine the registration. As shown in FIG. 8, onceregistered, the surgeon navigates the placement of the cutting guide 217using the combination of “snap-on” geometric design and the trackingsystem coupled to visual feedback This allows assessment of inaccuraciesrelated to soft tissue interference, iatrogenic malpositioning,anatomical changes since acquiring original CT scan data, and/orimperfections in cutting guide design or additive manufacturing process.

Self-drilling screws affix the cutting guide to the patient's skeletonto ensure osteotomies are performed along pre-defined planes, maximizingbony congruity. After dissecting the donor's maxillofacial fragment andpreparing the recipient's anatomy, the surgical team transfers thefacial alloflap. The system is configured to track the finalthree-dimensional placement of, for example, the Le Fort-based alloflapproviding real-time visualization such as that shown in FIG. 5A-5B. Thisprovides real-time visualization of important structures such as neworbital volumes (vertical limit of inset), airway patency (posteriorhorizontal limit of inset), and facial projection (anterior horizontallimit of inset). Once confirmed, the surgeon fixates the donor alloflapto the recipient following conventional techniques with plates andscrews.

Accordingly, returning to FIG. 2A-2G, there is a system 2000 fortracking donor and recipient surgical procedures simultaneously. Thesystem can include a donor sub-system 200-D, a recipient sub-system200-R and a communications link (indicated by the horizontaldotted-line) such as a communication link that provides TCP/IP datatransfer between the donor and recipient sub-systems. The donorsub-system can include a first computer workstation 215-D, a firstcranial reference module 205-D, a first cutting guide 207-D forattaching to a preselected location of a donor skeleton 206, a firstfragment reference module 201-D′, and a first tracker 213-D. The firstcutting guide 207-D can include an attachment surface 219-R configuredfor attaching to a skeletal feature, and a navigation surface 217-Dconnected to the attachment surface and comprising a trackable referencegeometry. The first tracker 213-D may be configured to be incommunication with the first computer workstation, for example, via acommunications link. The first tracker can be configured to track, forexample via IR optical tracking, a location of a portion of the firstcranial reference module, a portion of the first cutting guide and aportion of the first fragment reference module. The recipient sub-system200-R can include a second computer workstation 215-R, a second cranialreference module 205-R, and a second tracker 213-R. The second tracker213-R can be configured to be in communication with the second computerworkstation, for example, via a communications link. The second trackercan be configured to track, for example, via IR optical tracking, alocation of a portion of the second cranial reference module. Thecommunications link can connect the first computer workstation and thesecond computer workstation such that the first computer workstation andsecond computer workstation are able to communicate.

The recipient sub-system 200-R can further include a second fragmentreference unit 201-R. The second tracker 213-R can further be configuredto track a location of a portion of the second fragment unit.

The recipient sub-system 200-R can further include a second cuttingguide 219-R for attaching to a preselected location of a recipientskeleton 208. The second tracker 213-R can further be configured totrack a location of a portion of the second cutting guide.

Additionally, when a surgeon has removed the donor skeletal fragmentfrom the donor, it can then be transferred for attachment onto therecipient. Accordingly, the second tracker 213-R can be furtherconfigured to track a location of a portion of the first cutting guide207-D so that it can be matched relative a position of the secondcranial reference module 205-R.

The first cranial reference unit, the second cranial reference unit, orboth the first and second cranial reference units can include akinematic mount 205 as described above.

Using the system of FIGS. 2A-2G, it is possible to execute a surgicalmethod, such as the surgical method described in FIG. 3. For example, instep 302 a donor, recipient and transplant type are identified. CT/CTAscans of both the donor and recipient are collected and 3D models arecreated in step 304. The donor and recipients are prepared for surgerywith the creation of skin incisions in step 306. The method continues at307 with attachment of reference guides and performing registration. Forexample, a first cranial reference unit can be attached to a donorskeleton, a first fragment reference unit can also be attached to thedonor skeleton at a location that is different that of the first cranialreference unit. The locations of the first cranial reference unit andthe first fragment reference unit can be tracked with a first tracker.3D reconstructions of the donor skeleton can be constructed showing afirst virtual cranial reference unit and first virtual fragmentreference unit superimposed on the first 3D reconstruction at locationsthat correspond to relative positions of the first cranial referenceunit and the first fragment reference unit.

A second cranial reference unit can be attached to a recipient skeleton.A second location of the second cranial reference unit can be trackedwith a second tracker. A second 3D reconstruction of the recipientskeleton can be created with a second virtual cranial reference unitsuperimposed on the second 3D reconstruction at a location thatcorresponds to a location of the second cranial reference unit. At 308,vessels and nerves are dissected and exposed. At this stage, navigationof the patient-specific cutting guides can occur, with plan revision andupdates provided periodically. For example, a first cutting guide, suchas a patient-specific cutting guide according to the descriptionsprovided above, can be attached onto the donor skeleton at a preselectedlocation such as that corresponding to a planned cut-plane. The locationof the first cutting guide can be tracked with the first tracker. Afirst virtual cutting guide can be superimposed on the first 3Dreconstruction at a location that corresponds to a location of the firstcutting guide relative to the location of the first cranial referenceunit or the location of the first fragment reference unit.

A first virtual fragment can be formed by segmenting the 3Dreconstruction of the donor skeleton at a location adjacent to the firstvirtual cutting guide. The first virtual fragment can be superimposed onthe second 3D reconstruction of the recipient skeleton.

At step 310, a surgeon can perform an osteotomy on the donor skeleton toremove the first fragment but cutting the skeleton along a cutting pathdefined by the first cutting guide. Upon transferring the removedskeletal fragment from the donor, the first cutting guide can betracked, by the second tracker, for example, when the fragment isbrought near the recipient for attachment. The surgeon can then navigateplacement of the cutting guide as it is dynamically tracked at step 311,and will receive feedback from the system such as by referring to afirst virtual fragment that is superimposed on the second 3Dreconstruction to form a hybrid 3D reconstruction. At step 312, thefirst fragment can then be attached to the recipient skeleton via knownsurgical methods and the incisions can be sutured in step 314.

The step of superimposing the first virtual fragment on the second 3Dreconstruction of the recipient skeleton can include performing anautomated cephalometric computation for the hybrid reconstruction. Infact, the step of superimposing the first virtual fragment on the second3D reconstruction can include providing a communications link between afirst workstation on which the first 3D reconstruction is displayed anda second workstation on which the second 3D reconstruction is displayed,and initiating a data transfer protocol that causes the firstworkstation and the second workstation to send electronic signalsthrough the communications link.

Surgical methods of the embodiments described above can also includeattaching a second cutting guide at a preselected location on therecipient skeleton. The second cutting guide can also include featuresof the cutting guide described above.

For the surgical methods of embodiments described herein the donorskeleton can include a male skeleton or a female skeleton and therecipient skeleton comprises a female skeleton. Alternatively, the donorskeleton can include a male or female skeleton and the recipientskeleton can include a male skeleton.

Surgical methods of the embodiments can further include steps forassessing a size-mismatch between the donor skeleton and the recipientskeleton by measuring a dorsal maxillary interface between the firstfragment and recipient skeleton. In an embodiment, the surgical methodcan include selecting a location of the first fragment onto therecipient skeleton that minimizes dorsal step-off deformity at the areaof osteosynthesis.

In an embodiment, the first cutting guide, second cutting guide or boththe first cutting guide and the second guide comprise concentric cuttingguides.

Surgical methods of embodiments can further include mapping the vascularsystem on the facial anatomy of both the recipient and the donor andsuperimposing corresponding virtual representations of the vascularsystem and the facial anatomy onto the first 3D representation, such asshown in FIG. 4B

Surgical methods of embodiments can include a method for registration ofa preoperative model, for example a model reconstructed from CT data, todonor and recipient anatomy. Such a method can include: creating aplurality of indentations on the donor skeleton, creating a plurality ofvirtual markers on the first 3D reconstruction of the donor skeletoncorresponding to the locations of the indentations on the donorskeleton, placing a trackable object on at least one of the plurality ofindentations, and determining whether a subsequent location of thevirtual markers is within a predetermined tolerance relative to anactual subsequent location of the indentations.

EXAMPLES Example 1

Live transplant surgeries (n=2) between four size-mismatched swineinvestigated whether or not an embodiment could actually assist asurgical team in planning and in executing a desired surgical plan. Asshown in FIGS. 9A-9B, the first live surgery confirmed the proposedutility of overcoming soft and hard tissue discrepancies related tofunction and aesthetics. The final occlusal plane within the firstrecipient was ideal and consistent with the virtual plan as seen onlateral cephalogram as shown in FIG. 10C. Pre-operative functionalpredictions of donor-to-recipient occlusion were realized based oncephalometric analyses as shown in FIG. 9C performed both before andafter surgery. Soft tissue inconsistencies of the larger-to-smallerswine scenario were also reduced following the predicted movements offace, jaw and teeth as shown in FIG. 10D.

The second live surgery showed improved success as compared to itspredecessor due to surgeon familiarity and technology modifications.System improvements and growing comfort of the surgeons led to reducedoperative times for both donor and recipient surgeries. Overall thesurgical time reduced from over 14 hours to less than 8 hours due toimproved surgical workflow and increased comfort with a system of anembodiment.

Based on the results obtained in the live and plastic bone surgeries,the functions associated with setting up a system of an embodiment(attaching references, performing registration, attaching cuttingguides) adds about 11 minutes to the total length of surgery.

The system also recorded information, such as rendering informationwhich can be stored in a storage medium of a workstation, relating thedonor fragment 1002 to the recipient 1010 qualitatively as shown bycolor mismatch 1004, which matched the post-operative CT data as shownin FIG. 10. The recipient cutting guide 1107′ was not placed as planned1107, however, due to an unexpected collision between cranial referencemount and recipient cutting guide as shown in FIGS. 11A-11B. In thiscase, there was anterior translation of the cutting guide (toward thetip of the swine's snout) by approximately 4 cm.

Overall, the donor 1106 and recipient craniums (n=4) 1108 wereregistered successfully to the reference bodies for both live surgeries.The model to patient registration error across the surgeries was 0.6(+/−0.24) mm. The cutting guide designs of the embodiments proved highlyuseful in carrying out the planned bone cuts, which compensated forsize-mismatch discrepancies between donor and recipient. Marking spheresfixated to the guides allowed real-time movement tracking and “on-table”alloflap superimposition onto the recipient thereby allowingvisualization of the final transplant result.

Example 2

Female and male donor heads (n=2), double-jaw, Le Fort III-basedalloflaps were harvested using handheld osteotomes, a reciprocating saw,and a fine vibrating reciprocating saw. Both osteocutaneous alloflapswere harvested using a double-jaw, Le Fort III-based design (acraniomaxillofacial disjunction), with preservation of the pterygoidplates, incorporating all of the midfacial skeleton, complete anteriormandible with dentition, and overlying soft tissue components necessaryfor ideal reconstruction.

Prior to transplantation, both scenarios were completed virtually giventhe gender-specific challenges to allow custom guide fabrication asshown in FIGS. 12A-H. Once assimilated, the donor orthognathic two-jawunits were placed into external maxilla-mandibular fixation (MMF) usingscrew-fixated cutting guides to retain occlusal relationships during themock transplants as shown in FIGS. 13A-D.

As shown in FIGS. 13A-D, 14A-14B, an embodiment of a cutting guide 1307can include a frame 1307′ with at least one attachment surface 1319, forexample 1 to 6 attachment surfaces, configured for attaching the cuttingguide to a skeletal feature. The cutting guide can include a navigationsurface 1317 (not shown in FIG. 13) connected to the frame. Thenavigation surface can include a reference geometry that can be trackedby a tracker, for example, via IR optical tracking. The at least oneattachment surface 1319 can include a contoured surface corresponding tocontours of portions of the skeletal feature, for example, such as thecontours of a skeletal feature that intersect a planned-cut plane asindicated by 1319′ in FIGS. 12A-H. The at least one attachment surface1319 can be detachably connected to a skeletal feature. The at least oneattachment surface 1319 can be detachably connected to an attachmentguide 1341. The attachment guide 1341 can be detachably connected to aportion of the frame 1307′. For example, attachment guides 1341 can bedetachably connected via slots integrated into frame 1307′, or held inplace against frame 1307 with screws or the like. In another embodiment,attachment guides 1341 are formed as portions of frame 1307′ but can beremoved. The frame can have a ring-like shape (as shown in FIG. 13) orcan have a cylinder-like shape (as shown in FIG. 14A). Frame 1307′having a cylinder like shape can have a bottom surface 1307″ that restsagainst a patient's soft tissue to provide support for the frame.

For example, during a surgical procedure, 3D reconstructions of portionsof a donor skeleton are created. Planned cutting planes are selected anda cutting guide with attachment surfaces having a contoured surfacecorresponding to contours of portions of the skeletal feature, forexample, such as the contours of a skeletal feature that intersect aplanned-cut plane, is designed. The designed cutting guide ismanufactured via, for example, an additive manufacturing process. Thedesigned cutting guide with an integrated navigation surface is attachedto the patient. For example, the cutting guide can be designed such thatit has a snap-on fit over the skeletal feature, which can be furthersecured to the skeletal feature with set screws. A surgeon removes adonor skeletal fragment with the cutting guide attached to the fragment.The donor skeletal fragment is then attached to the recipient. As thedonor skeletal fragment is attached to the recipient, the attachmentsurfaces are removed from the donor fragment. For example, each of theattachment guides 1341 with a corresponding attachment surface 1319 canbe detached from the frame 1307′. As this occurs, a cylindrical shapedframe 1307′ has a bottom surface 1307″ that rests against the softtissue of the patient to provide stability for the remaining portions ofthe cutting guide and to hold the navigation surface 1317′ in place.

While the invention has been illustrated respect to one or moreimplementations, alterations and/or modifications can be made to theillustrated examples without departing from the spirit and scope of theappended claims. In addition, while a particular feature of theinvention may have been disclosed with respect to only one of severalimplementations, such feature may be combined with one or more otherfeatures of the other implementations as may be desired and advantageousfor any given or particular function.

For example, the embodiments described herein can be used for navigationand modeling for osteotomy guidance during double-jaw facetransplantation, single-jaw maxillofacial transplantation, and any otherneurosurgical, ENT/head and neck surgery, or oral maxillofacial surgicalprocedure alike.

Embodiments described herein can include platform for preoperativeplanning and intraoperative predictions related to softtissue-skeletal-dental alignment with real-time tracking of cuttingguides for two mismatched jaws of varying width, height and projection.Additional safeguards, such as collection of confidence points, furtherenable intraoperative verification of the system accuracy. This, inaddition to performing real-time plan verification via tracking anddynamic cephalometry, can considerably increase the robustness of thesystems described herein. Moreover, systems of embodiments can include amodular system that allows additional functionality to be continuallyadded.

Embodiments described herein can include an approach for resolvingconflicts in case of position discrepancies between the placement of theguide and the guide position prompted by the navigation software. Suchdiscrepancy may be due to either the guide (soft tissue interference,iatrogenic malpositioning, changes since the CT data was obtained orimperfections in cutting guide construction/printing), and/or thenavigation system (e.g. registration error, or unintended movement ofthe kinematic markers). To resolve these source(s) of discrepancy, fourindentations can be created on a bone fragment (confidence points) wherea reference kinematic marker is attached. At any time during anoperation, a surgeon can use a digitizer and compare the consistency ofthe reported coordinates of the indentations via navigation to theircoordinates with respect to a virtual computer model.

Embodiments described herein can include a system that providesreal-time dynamic cephalometrics and masticatory muscle biomechanicalsimulation for both planning and intraoperative guidance to ensure idealoutcomes in craniomaxillofacial surgery.

FIG. 15 is an example method of a computer-implemented method forcomputer-assisted planning of a transplant surgery 1500, according tothe present teachings. At 1505, the method can include obtaining acomputer-readable representation of a donor skeletal fragment, as shownin FIG. 12A. The computer-readable representation of a donor skeletalfragment can be created based, at least in part, on one or more medicalimaging techniques. Also, the computer-readable representation of thedonor skeletal fragment can comprise one or more of: a vascular model ora neural model of the donor skeletal fragment, as shown in FIG. 4B. Thedonor skeletal fragment can be from the same patient or from anotherpatient or source.

At 1510, the method can include obtaining a computer-readablerepresentation of a recipient skeletal fragment, as shown in FIG. 12B.Similarly to FIG. 12A, the computer-readable representation of a donorskeletal fragment of FIG. 12B can be created based, at least in part, onone or more medical imaging techniques. Again, the computer-readablerepresentation of the recipient skeletal fragment can comprise one ormore of: a vascular model or a neural model of the recipient skeletalfragment, as shown in FIG. 4B.

In some aspects, the computer-readable representation of the recipientskeletal fragment and the donor skeletal fragment can comprises asegmented 3D reconstruction model. The segmented 3D model can be createdusing the one or more medical imaging techniques and a segmentationalgorithm. For each voxel of the segmented 3D reconstruction model ofthe recipient skeletal fragment and the donor skeletal fragment, anassociated anatomical attribute can be associated thereto to classify ananatomy for which each voxel represents. For example, each voxel mayinclude anatomical characteristic consistent with, but are not limitedto, bone or soft tissues, such as cartilage, neural and/or vascularstructures.

At 1515, the method can include determining one or more surgical cuttingplanes on the computer-readable representation of the donor skeletalfragment from which a portion of the donor skeletal fragment from thecomputer-readable representation of the donor skeletal fragment will beharvested. For example, as shown in FIGS. 12D and 12E, cutting planes1319′ are shown on the computer-readable representations. In someaspects, the cutting planes may be associated with or coincide with oneor more fracture planes commonly encountered in LeFort-type fractures,such as LeFort I, II, and/or III fractures. Once determined, the one ormore surgical cutting planes can be positioned onto thecomputer-readable representation of the donor skeletal fragment.

At 1520, the method can include determining one or more virtual cuttingguides based on the one or more surgical cutting planes to be attachedto the computer-readable representation of the donor skeletal. The oneor more cutting guides can be used to assist the surgeon in carrying outthe correct surgical incision based, at least in part, on the one ormore surgical cutting planes. At 1525, the method can include performinga virtual osteotomy to separate the portion of the donor skeletalfragment from the computer-readable representation of the donor skeletalfragment from a remainder portion of the donor skeletal fragment basedon a position of the one or more virtual cutting guides that areattached to the computer-readable representation of the donor skeletalfragment. For example, as shown at 217-D in FIG. 8A, cutting guides canbe used to assist the surgeon during the planning and actual surgery, incorrectly removing the donor skeletal fragment based, at least in part,on the surgical cutting planes that were determined.

At 1530, the method can include positioning the donor skeletal fragmentwithin a transplant region of the recipient skeletal fragment. Forexample, as shown in FIGS. 12G and 12H, the donor skeletal fragment isshown positioned onto the recipient skeletal fragment. In some aspects,movement of the donor skeletal fragment of the computer-readablerepresentation can be tracked during the positioning. The tracking canbe performed by identifying a set of cephalometric landmarks associatedwith the hybrid computer-readable representation. A set of cephalometricmetrics can then be calculated for the set of cephalometric landmarksthat are identified. The surgeon can then determine whether anacceptable result of the surgery being planned has been achieved based,at least in part, on the set of cephalometric metrics that arecalculated. The set of cephalometric landmarks comprise one or more of:Gonion (“Go”), Nasion (“N”), A point (“A”), B point (“B”), Sella (“S”),Menton (“M”), left/right Zygoma (“ZY”), Os occipital (“OCC”). Othercephalometric landmarks can also be used.

At 1535, the method can include creating a hybrid computer-readablerepresentation comprising the recipient skeletal fragment and theportion of the donor skeletal fragment during or after the positioning.At 1540, the method can include providing the hybrid computer-readablerepresentation as an output. FIG. 12H shows an example of the hybridcomputer-readable representation. As the donor fragment is positionedaround the recipient, the hybrid computer-readable representation andthe output can be updated based, at least in part, on the movement beingtracked. Also, during this planning process, the one or more surgicalcutting planes or cutting guides can be modified based on whether thesurgeon considers the positioning and placement of the donor skeletalfragment on the recipient an acceptable result. This process can beaided by comparing the set of cephalometric metrics that were calculatedwith a set of baseline cephalometric metrics. Additionally, the updatesand/or real-time feedback can be in a form such as a change inappearance of a visual indicator on a hybrid model as the donor skeletalfragment is mated with the recipient skeletal fragment, as is shown anddescribed in relation to FIGS. 2B, 2C, 11A, and 11B, where the color iscaused to change from one color to another color. For example in FIGS.2B and 2C, the color changes from red to green when the donor skeletalfragment is properly mounted onto the recipient. By way of one example,the donor skeletal fragment can comprise at least a maxilla or mandibleand the real-time feedback that is provided can comprise providing avisual indication as to how well one or more teeth of the hybridmaxilla-mandible combination match.

FIG. 16 illustrates a schematic view of such a computing or processorsystem 1600, which can include the computers 215-D and 215-R, accordingto an embodiment. The processor system 1600 may include one or moreprocessors 1602 of varying core configurations (including multiplecores) and clock frequencies. The one or more processors 1602 may beoperable to execute instructions, apply logic, etc. It will beappreciated that these functions may be provided by multiple processorsor multiple cores on a single chip operating in parallel and/orcommunicably linked together. In at least one embodiment, the one ormore processors 1602 may be or include one or more GPUs.

The processor system 1600 may also include a memory system, which may beor include one or more memory devices and/or computer-readable media1604 of varying physical dimensions, accessibility, storage capacities,etc. such as flash drives, hard drives, disks, random access memory,etc., for storing data, such as images, files, and program instructionsfor execution by the processor 1602. In an embodiment, thecomputer-readable media 404 may store instructions that, when executedby the processor 1602, are configured to cause the processor system 1600to perform operations. For example, execution of such instructions maycause the processor system 1600 to implement one or more portions and/orembodiments of the method described above.

The processor system 1600 may also include one or more networkinterfaces 1606. The network interfaces 1606 may include any hardware,applications, and/or other software. Accordingly, the network interfaces1606 may include Ethernet adapters, wireless transceivers, PCIinterfaces, and/or serial network components, for communicating overwired or wireless media using protocols, such as Ethernet, wirelessEthernet, etc.

The processor system 1600 may further include one or more peripheralinterfaces 1608, for communication with a display screen, projector,keyboards, mice, touchpads, sensors, other types of input and/or outputperipherals, and/or the like. In some implementations, the components ofprocessor system 1600 need not be enclosed within a single enclosure oreven located in close proximity to one another, but in otherimplementations, the components and/or others may be provided in asingle enclosure.

The memory device 1604 may be physically or logically arranged orconfigured to store data on one or more storage devices 1610. Thestorage device 1610 may include one or more file systems or databases inany suitable format. The storage device 1610 may also include one ormore software programs 1612, which may contain interpretable orexecutable instructions for performing one or more of the disclosedprocesses. When requested by the processor 1602, one or more of thesoftware programs 1612, or a portion thereof, may be loaded from thestorage devices 1610 to the memory devices 1604 for execution by theprocessor 1602.

Those skilled in the art will appreciate that the above-describedcomponentry is merely one example of a hardware configuration, as theprocessor system 1600 may include any type of hardware components,including any necessary accompanying firmware or software, forperforming the disclosed implementations. The processor system 1600 mayalso be implemented in part or in whole by electronic circuit componentsor processors, such as application-specific integrated circuits (ASICs)or field-programmable gate arrays (FPGAs).

The foregoing description of the present disclosure, along with itsassociated embodiments and examples, has been presented for purposes ofillustration only. It is not exhaustive and does not limit the presentdisclosure to the precise form disclosed. Those skilled in the art willappreciate from the foregoing description that modifications andvariations are possible in light of the above teachings or may beacquired from practicing the disclosed embodiments.

Additional Embodiments

Osseointegrated Dental Implants

Patients with poor or missing dentition require dental implants toimprove mastication. A popular modality with increasing indicationsinclude “osseointegrated dental implants”. Oseeointegrated dentalimplants can include, and may consist of, a two-piece permanent implantdevice, which is placed into either the maxilla or mandible skeletonwith a power drill for placement and stability. A second piece, in theshape of a tooth for example, is screwed onto the secure base. Anembodiments of the CAPE system described above can be used to providethe dentist or surgeon real-time cephalomteric feedback in an effort torestore ideal occlusion and predict optimized mastication withbiomechanical predictions—as similar to maxillofacial transplantation.As such, the dentist or surgeon placing them needs to know the bonestock quality of the jaw(s) and angle to place the framework. Insummary, the CAPE system described above may be applied to thisspecialty.

Osseointegrated Craniofacial Prosthetics

Patients with severe cranial or facial disfigurement may be poorsurgical candidates due to overwhelming co-morbities and/or because ofan accompanying poor prognosis. Therefore, to help return these patientsinto society, some use craniofacial prosthetics as a way to restore“normalcy”. Application of these three-dimensional prosthetics replacingabsent craniofacial features (ie. nose, eye, etc) may either behand-molded/painted by an anaplastologist or printed with 3D technologyby a prostheticraniofacialian. Either way, in an embodiment, the CAPEsystem described above can provide a one-stop solution for patientsrequiring alloplastic and/or bioengineered prosthetic reconstruction forlarge craniomaxillofacial deformities. The craniofacial implants can betracked as similar to a donor face-jaw-teeth segment described above.For example, pre-placement images of the prosthetic could be fabricated,and surgical plans could be optimized since these appliances are placedwith osseointegrated devices as similar to dental implants describedabove—with rigid plates and screws. As such, the surgeon placing themneeds to know the bone stock quality and angle to place the framework,and also needs to known with visual feedback as to the ideal position inthree-dimensional space. In summary, the CAPE system described here maybe applied to this specialty.

Craniomaxillofacial Trauma Reconstruction

Patients suffering from acute or chronic facial disfigurement is acommon type seen by the craniomaxillofacial surgeon. Both penetratingand/or blunt trauma may cause significant damage to the underlyingfacial skeleton. As such, in an embodiment, the CAPE system technologydescribed herein allows the surgeon to assess and optimize bone fragmentreduction and reconstruction with real-time feedback. In addition,fractures affecting the jaws can be aided by real-time cephalometrics inhopes to restore the patient back to their pre-trauma angle/measurements(as a way to assure proper occlusion). Navigation, as described above inan embodiment of the CAPE system, can be exceptionally helpful for orbitfractures around the eye or cranial fractures around the brain, sincethe nerve anatomy is delicate and consistent—which makes it applicableto the CAPE system. In summary, a surgeon (including the likes of aPlastic surgeon, ENT surgeon, oral/OMFS surgeon, oculoplastic surgeon,neurosurgeon) reducing craniofacial fractures needs to know the bonestock quality remaining, where plates/screws are best placed, and theoptimal plan prior to entering the operating room. Therefore, the CAPEsystem described within may be applied to this area as well.

Neurosurgical Procedures

Neurosurgeons frequently perform delicate craniotomies for access forbrain surgery. Currently, there are several navigational systemsavailable. However, none of the conventional systems include featuresdescribed in the embodiments of the CAPE platform as described above.That is, the conventional systems lack the ability to assist bothpre-operatively with planning AND with intra-operative navigation forexecution assistance. In addition, the current neurosurgery systemsrequire the head to be placed in antiquidated “bilateral skull clamppins” during the entire surgery. This means that before eachneurosurgery procedure starts, a big 3-piece clamp is crunched onto theskull of the patient to make sure the head does not move during surgery,particularly to allow for use of the conventional navigation systems.However, embodiments of the CAPE system, such as those described above,use a small, modified rigid cranial reference mount which removes theneed for using a big, bulky clamp from the field and allows the surgeonto rotate the patient's head if and when needed. To a craniofacialplastic surgeon, who often is consulted to assist with simultaneousscalp reconstruction, elimination/removal of such pins from the surgicalfield is a huge advantage. For example, elimination of the pins makesscalp reconstruction in the setting of neurosurgery much safer since thepins aren't present to hold back mobilization and dissection of thenearby scalp—which is needed often for complex closure. It also, reducesthe risk of surgical contamination since the current setup with pins isbulky and makes surgical draping and sterility much more difficult andawkward. A small cranial mount as part of the CAPE system is a hugeadvancement for the field. As such, the CAPE system described herein maybe applied to neurosurgical procedures as well.

Congenital Deformity Correction

Unfortunately, newborns are commonly born with craniofacial deformitiesto either maternal exposure or genetic abnormalities. As such, they mayhave major development problems with their skeleton and the overlyingstructures (eyes, ears, nose) may therefore appear abnormal. Inaddition, newborns may suffer from craniosynostosis (premature fusing oftheir cranial sutures) which causes major shifts in the shape of theirhead at birth. In an embodiment, the CAPE system described above, can beutilized to address such congenital deformities, irrespective ofetiology. For example, if a 16 year old needs to have major Le Fortsurgery to move the central facial skeleton into better position forwardto improve breathing, mastication, and appearance, use of the CAPEsystem technology for both pre- and intra-operatively provides a hugeadvancement for the field.

Head/Neck and Facial Reconstruction (ENT Surgery)

Head and neck surgeons in the specialty of Otolarygology (ENT) arefrequently reconstructing facial skeletons. Reasons include post-tumorresection, facial trauma, aesthetic improvement, congenital causesand/or functional improvement (nose, mouth, eyes, etc). Therefore, thisspecialty would greatly benefit from use of the CAPE system technologydescribed herein. For example, in an embodiment, use of the CAPE systemcan help a wide range including such instances as post-trauma fracturereduction/fixation, free tissue transfer planning and execution (ie.Free flap reconstruction with microsurgical fibula flaps for large bonedefects where the leg bone receives dental implants for jawreconstruction), smaller jaw reconstruction cases with implantmaterials, and/or anterior skull base reconstructions with neurosurgeryfollowing tumor resection. This specialty is very diverse, and thereforethe CAPE system's easy adaptability can help make it greatly valuable tothis group of surgeons.

Orthognathic Surgery

Orthognathic surgery describes any of surgical procedure type moving thejaw and/or jaw-teeth segments. This is most commonly performed by eitheroral surgeons, oral-maxillofacial surgeons (OMFS), or plastic surgeons.It is done currently both in the hospital as an insurance case or in theoutpatient setting for a fee-for-service. It may be indicated forenhanced mastication, improved aesthetics, and/or both reasons. Havingthe ability to plan and predict jaw movements based on biomechanicalmuscle (ie. External) forces will be immensely valuable to this field.In an embodiment, surgeons can utilize the CAPE system described aboveto predict functional jaw movements both at time of surgery and aftersurgery (1, 5, 10, 20 years post-op). In addition, in an embodiment, asurgeon can utilize the CAPE system to provide real-time cephalometricfeedback, which provides an advancement not seen in the conventionalsystems. In comparison, for the last several centuries, oral surgeonshave used splints fabricated in the dental lab pre-operatively forassistance in the operating room—to help confirm dental alignment asplanned. This takes time (4-6 hours to make by hand), effort (can bedone virtually nowadays but is very expensive) and money. In contrast tothe conventional systems, Surgeons utilizing the CAPE system, such as anembodiment described above, can go to the operating room withpre-fabricated cutting guides and tracking instruments, cut the jawswhere planned, and then match the teeth on the table based on real-timecepholmetric feedback and biomechanical jaw simulation to predictpost-operative mastication—unlike ever before. For example, use of theCAPE system will allow surgeons to know instantaneously if the aestheticand functional angles/measurements are ideal and where they should be.In addition, the CAPE system is able to supply palatal cutting guidesand pre-bent metal fixation plates (as opposed to the conventionalmethods that require handbending each plate for proper shape). Insummary, the CAPE system will be a “game-changer” for orthognathicsurgery.

“Computer-Assisted Cranioplasty”

At least some embodiments described herein can be used for the immediatesurgical repair of large cranial defects (>5 cm²). For example,embodiments described herein may be used for designing, forming andimplanting customized craniofacial implants following benign/malignantskull neoplasm (tumor) resection (i.e. referred to as “single-stageimplant cranioplasty”). Currently, it is challenging to reconstruct suchpatients with pre-fabricated implants using conventional methods sincethe actual size/shape of the defect site is unknown until the tumor isremoved. Accordingly, use of a computer-assisted surgical system of anembodiment may significantly reduce the intraoperative time used forreshaping/resizing the customized implant. For example, embodimentsprovide visualization related to the tumor, the resulting skull defect,and the reshaped implant for exact positioning. In other words, in anembodiment, a Computer-Assisted Planning and Execution (CAPE) systemthat can be utilized for Le Fort-based, Face-Jaw-Teeth transplantationmay also be used for improving both the pre-operative planning andintra-operative execution of single-stage implant cranioplasties.Cranioplasties may be performed to reconstruct large defects followingstroke, trauma, aneurysmal bleeding, bone flap removal for infection,and oncological ablation. However, oncological defects are commonlyreconstructed with “off-the-shelf” materials, as opposed to using apre-fabricated customized implant—simply because the exact defectsize/shape is unknown. With this in mind, embodiments described hereininclude a computer-assisted algorithm that may allow surgeons toreconstruct tumor defects with pre-customized cranial implants (CCIs)for an ideal result.

Nearly 250,000 primary brain tumors/skull-based neoplasms are diagnosedeach year resulting in a range of 4500-5000 second-stage implantcranioplasties/year. Unfortunately, the common tumor defect cranioplastyis reconstructed with on-table manipulation of titanium mesh, liquidpolymethylmethacrylate (PMMA), liquid hydroxyapatitie/bone cement (HA)or autologous split-thickness calvarial bone grafts (ref), which forcesthe surgeon to shape/mold these materials to an approximate size/shape.Expectantly, this results in some form of craniofacial asymmetry and apost-operative appearance which is suboptimal. Furthermore, thedifficult shaping process may take several hours—which in turn increasesanesthesia, total blood loss, risk for infection, morbidity, and allcosts associated with longer operative times. Therefore, there issignificant opportunity to extend this CAPE to thousands of patients.

In 2002, the advent of computer-aided design and manufacturing (CAD/CAM)was used for the first time to pre-emptively match the contralateral,non-operated skull for ideal contour and appearance, which provided forthe use of CCIs. However, cranioplasties with such CCIs can only beperformed as “second stage” operations during which a clinician, such asa surgeon, ensures that the CCI fits perfectly into the skull defect.Recent developments have demonstrated the feasibility of CCIs for“single-stage cranioplasty”, but this involves using a handheld bur toshave down the pre-Ofabricated implant artistically. However, challengesin both assessing and predicting each tumor-resection deformitypre-surgery still limits the applicability of CCIs in this patientpopulation. For example, challenges such as 1) unknown exact tumor size,2) unknown growth from time of pre-op CT scan-to-actual day of surgery,and 3) the unknown resection margins needed to minimize localrecurrence. For these cases, the CCI would need to be reshaped/resizedintraoperatively from a size slightly larger than expected—which is aprocess that may take several (2-4) hours. However, there are noestablished planning and execution systems available to assist thesesingle-stage reconstructions. Accordingly, embodiments described hereinmay be used by surgeons in performing single-stage cranioplastyfollowing oncological resection. In other words, embodiments includealgorithms for real-time updates related to single-stage customizedimplant cranioplasty. For example, in an embodiment, there is aComputer-Assisted Planning and Execution (CAPE) system, which is aSINGLE, seamless platform capable of being used for both planning(pre-op use) and navigation (intra-op use) which overcomes thelimitations of conventional systems that do either one or the other. Inaddition, embodiments include novel hardware such as trackable cuttingguides and rigid cranial reference mount. The CAPE architecture willprovide reconstructive surgeons all the necessary algorithms forreal-time updates related to single-stage customized implantcranioplasty.

TABLE 1 Comparison of CAPE and Competitive Solutions Innovation Med SurgPraxim/ Smith & Group Brainlab Services Medtronic Paritic Ortho SurgSiemens Nephew Stryker Zimmer CAPE Virtual Planning ✓ X ✓ X X X X X X X✓ Navigation ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Real time X X X X X X X X X X ✓Cephalometrics Trackable X X X X X X X X X X ✓ Cutting guidesBiomechanical X X X X X X X X X X ✓ Simulation Multiple Stations X X X XX X X X X X ✓

Furthermore, to the extent that the terms “including”, “includes”,“having”, “has”, “with”, or variants thereof are used in either thedetailed description and the claims, such terms are intended to beinclusive in a manner similar to the term “comprising.” As used herein,the phrase “one or more of”, for example, A, B, and C means any of thefollowing: either A, B, or C alone; or combinations of two, such as Aand B, B and C, and A and C; or combinations of three A, B and C.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

We claim:
 1. A computer-implemented method for computer-assistedplanning of craniomaxillofacial surgery, the method comprising:intraoperatively studying a hybrid computer-readable representationcomprising a computer-readable representation of a recipient skeletalfragment and a computer-readable representation of an implant, thehybrid computer-readable representation being created by: obtaining thecomputer-readable representation of the implant; obtaining acomputer-readable representation of a recipient skeletal fragment;positioning the computer-readable representation of the implant within aregion of the computer-readable representation of the recipient skeletalfragment; creating the hybrid computer-readable representationcomprising the computer-readable representation of the recipientskeletal fragment and the computer-readable representation of theimplant during or after the positioning; intraoperatively tracking theimplant and the recipient skeletal fragment; and fixating the implant tothe recipient skeletal fragment.
 2. The computer-implemented method ofclaim 1, wherein intraoperatively tracking includes providing areference unit for real-time surgical navigation assistance.
 3. Thecomputer-implemented method of claim 1, further includingintraoperatively navigating placement of cutting guides.
 4. Thecomputer-implemented method of claim 1, wherein tracking includes visualtracking.
 5. The computer-implemented method of claim 1, wherein ofintraaoperatively tracking includes tracking a final three dimensionalplacement of the implant.
 6. The computer-implemented method of claim 1,wherein the implant is a craniofacial implant.
 7. Thecomputer-implemented method of claim 1, wherein the craniomaxillofacialsurgery is a cranioplasty.
 8. The computer-implemented method of claim1, wherein the craniomaxillofacial surgery is a single-stage implantcranioplasty.
 9. The computer-implemented method of claim 1, wherein thecraniomaxillofacial surgery is a craniomaxillofacial reconstructivesurgery.
 10. The computer-implemented method of claim 1, wherein thecraniomaxillofacial surgery is an orthognathic surgery.